Saturday 30 June 2012 14.36 EDT
First published on Saturday 30 June 2012 14.36 EDT

Conventional wisdom has it that transport is not an election decider. However, this might be about to be tested.

Last week's confusion on fuel duty might be only the start. A map of marginal constituencies, where the next election will be decided, shows a concentration around outer London and the south-east, and in the outer suburbs of the other big cities.

Many of these seats have large numbers of rail commuters – so what happens to railways in those areas could have a big impact on what happens at the next election.

The government can claim that it is investing in these services, with the Thameslink and Crossrail projects under construction in London and electrification and upgrades of lines in the north of England.

However, it is still committed to above-inflation fare rises – 3% above RPI for each of the next two years, a rise of 24% on 2011 prices. As our Fair Fares Now campaign has pointed out, this will add hugely to costs for hard-working families, and contrasts with the government's willingness to stop fuel duty increases.

This opens up the field for a challenge from Labour, and the new policies represent a calculation that radical changes to the railways can be electorally popular. It will also feed on concerns that aspects of the current structure are not working, notably the buck-passing between different bits of the railway when things go wrong.

However, it's easy for transport policy to get lost in technicalities. The danger is that ownership, bureaucracy, spreadsheets and organograms end up dominating the debate. Instead, Labour – and the other parties – must put passengers at the centre of their policies, and show at the next election that their policies will lead to real improvements for the communities served by the railways.

Cheaper and simpler fares, discounts for part-time workers, oyster-style smartcards in every area, proper staffing, better stations and services that are reliable and frequent – all these need to be at the centre of the debate, along with the investment needed to increase capacity and rail freight.

Labour's emerging policy sets down a challenge. The next election might go to the party that convinces the electors in those key commuter marginals that it has the policies to improve their lives and give them value for money.